Sun Yingzhi, Wang Xinghuan, Xiao Menglin, Lv Shanshan, Cheng Mengjiao, Shi Feng
State Key Laboratory of Chemical Resource Engineering & Beijing Laboratory of Biomedical Materials & Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Langmuir. 2021 Apr 13;37(14):4276-4283. doi: 10.1021/acs.langmuir.1c00266. Epub 2021 Apr 1.
Macroscopic supramolecular assembly (MSA) is a new concept of supramolecular science with an emphasis on noncovalent interactions between macroscopic building blocks with sizes exceeding 10 μm. Owing to a similar noncovalently interactive nature with the phenomena of bioadhesion, self-healing, etc. and flexible features in tailoring and designing modular building blocks, MSA has been developed as a simplified model to interpret interfacial phenomena and a facile method to fabricate supramolecular materials. However, at this early stage, MSA has always been limited to hydrogel materials, which provide flowability for high molecular mobility to the interfacial binding. The extension to a wide range of materials for MSA is desired. Herein, we have developed a strategy of adjusting intrinsic properties (e.g., elastic modulus) of nonhydrogel materials to realize MSA, which could broaden the material choices of MSA. Using the widely used elastomer of poly(dimethylsiloxane) (PDMS) as building blocks, we have demonstrated the elastic-modulus-dependent MSA of PDMS based on the host/guest molecular recognition between supramolecular groups of β-cyclodextrin and adamantane. In the varied elastic modulus range of 0.38 to 3.84 MPa, we obtained the trend of the MSA probability decreasing from 100% at 0.38 MPa to 0% at 3.84 MPa. Meanwhile, in situ measurements of interactive forces between PDMS building blocks have supported the observed assembly phenomena. The underlying reasons are interpreted with the low-modulus flexible surfaces favoring for high molecular mobility to achieve interactions between multiple sites at the interface based on the theory of multivalency. Taken together, we have demonstrated the feasibility of directly adjusting the modulus of bulk materials to realize MSA of nonhydrogel materials, which may provide clues to the fast wet adhesion and new solutions to the additive manufacture of elastomer materials.
宏观超分子组装（MSA）是超分子科学中的一个新概念，它强调尺寸超过10μm的宏观构建单元之间的非共价相互作用。由于与生物粘附、自愈等现象具有相似的非共价相互作用性质，以及在定制和设计模块化构建单元方面具有灵活性，MSA已发展成为一种解释界面现象的简化模型和一种制备超分子材料的简便方法。然而，在这个早期阶段，MSA一直局限于水凝胶材料，水凝胶材料为界面结合提供了高分子流动性所需的流动性。人们期望将MSA扩展到更广泛的材料。在此，我们开发了一种调节非水凝胶材料固有性质（如弹性模量）以实现MSA的策略，这可以拓宽MSA的材料选择范围。使用广泛使用的聚二甲基硅氧烷（PDMS）弹性体作为构建单元，我们基于β-环糊精和金刚烷的超分子基团之间的主/客体分子识别，展示了PDMS的弹性模量依赖性MSA。在0.38至3.84MPa的不同弹性模量范围内，我们得到了MSA概率从0.38MPa时的100%下降到3.84MPa时的0%的趋势。同时，对PDMS构建单元之间相互作用力的原位测量支持了观察到的组装现象。基于多价理论，低模量柔性表面有利于高分子流动性以实现界面处多个位点之间的相互作用，从而解释了其潜在原因。综上所述，我们证明了直接调节块状材料的模量以实现非水凝胶材料的MSA的可行性，这可能为快速湿粘附提供线索，并为弹性体材料的增材制造提供新的解决方案。
